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Postings from September 2003
Elizabeth Mattijsen <liz@dijkmat.nl> wrote:
> At 01:04 +0200 9/8/03, Rafael Garcia-Suarez wrote:
> >Elizabeth Mattijsen wrote:
> > > If I build 21021 with:
> > > > -Accflags=-DNO_HASH_SEED
> >You can always do 'perl -V:ccflags'. That should be there.
>
> You learn something every day. Thanks, Rafael.
>
>
> I concocted the following check routine. Maybe this needs a home
> somewhere in a Util core library somewhere? If so, I'll supply a
> patch for the indicated library.
>
> I also made it print something in void context, so you'll be able to
> do one-liners such as:
>
> perl -Mwhatever -e is_hash_randomized
>
> (if is_hash_randomized in module whatever.pm would be exported, of course)
>
>
> Liz
>
>
> The code:
>
> #---------------------------------------------------------------------------
> # is_hash_randomized
> #
> # OUT: 1 undef (random sequence) or defined (repeatable with seed)
> #
> # Prints a string when called in void context.
>
> sub is_hash_randomized {
>
> # If we're called in void context
> # Call ourselves to get status
> # Show the world what it is
> # We're done now
>
> if (!defined wantarray) {
> my $seed = is_hash_randomized();
> print defined $seed ?
> qq{Repeatable hash sequences with seed "$seed".\n} :
> qq{Unrepeatable hash sequences.\n};
> return;
> }
>
> # We don't have any random sequences yet, as if seed "0"
>
> return 0 if $] < 5.008001;
>
> # Get the -Accflags= settings using this Perl executor
>
> open my $handle, "$^X -V:ccflags |"
> or die "Could not execute $^X -V:ccflags: $!\n";
> my $ccflags = <$handle>;
> close $handle;
Maybe better use:
require IO::Pipe;
my $pipe = IO::Pipe->new->reader($^X, "-V:ccflags");
my $ccflags = <$pipe>;
$pipe->close;
I think the code above does not handle a value for $^X =
"C:\Dokumente und Einstellungen\Perl\Bin\perl.exe" very well...
> # Return repeatable default if random sequences compiled out
> # Return random if switch settings reversed and environment variable set
> # Return whatever the environment variable indicates
>
> return 0 if $ccflags =~ m#-DNO_HASH_SEED#;
> return if $ccflags =~ m#-DUSE_HASH_SEED_EXPLICIT#
> and exists $ENV{PERL_HASH_SEED};
> $ENV{PERL_HASH_SEED};
> } #is_hash_randomized
Regards,
Slaven
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